Indicator switch mechanism for electric ranges and the like



May 5, 1953 K. M. HAMMELL INDICATOR SWITCH MECHANISM FOR ELECTRIC RANGES AND THE LIKE Filed Oct. 5l 1950 0 3 22 INVENTOR.

25mm /Yamea Patented May 5, 1953 nvnIcA'roR SWITCH MECHANISMEQR ELECTRIC RANGES ANnfrm: LIKE Kemper M; Hammell, Harrisburg, Pa., assignor to General Electric Company, a. corporation of New York Application October 31, 1950, Serial No. 193,258

(Cl. {E19-37) Claims.

This invention relates to electric ranges, andl in particular to improved means for closing' an electric circuit to a lamp or' other signalling device for identiiication of the switch associated with the. surface heating unit on which a cooking utensil has been placed.

In modern electric range design it is the pr'acf tice to locate the heating unit control switches on an upwardly extending wall or backs'pl'asher` at the rear of the cooking top. This places the switches away from the direct and radiated heat of the surface units, and where the units are grouped at one side of the cooking top affords an opportunity to remove the switches from the cooking zone to avoid concealment ofthe switches by the cooking vessels or steam emanating therefrom. Although the respective switches are appropriately marked as to the unit which each controls, the separation of the switch from its associated' surface unit makes it possible inadvertently to actuate the wrong switch.; and it isV thereforea principal object of my invention to provide signal circuit means effective whenever a cooking utensil is placed on a surface unit to energize a lamp or other signaling device located at the switch associated with that particular surface unit.

It is another objective of the invention to provide a signal switch organization for the surface units of electric ranges, in which the switch mem ber and its actuator will not interfere with. the normal manipulation of the surface unit asit is raised or otherwise handled to permit cleaning or the removal of the reflector pan. customarily placed beneath the unit, and are protected against damage during such manipulation.

It is a further objective of the invention to provide a signal circuit switch organization which is of such simple construction that it may be assembled and installed in mass production by unskilled labor but will,.nevertheless, be highly reliable in operation over a long service life.

In a presently preferred form of the invention I use a fully enclosed switch-for example, amer-- cury type switch-pivotally mounted on a brack' et directly associated with the mounting of the surface unit in the range. The switch actuator comprises a lever pivotally axed to the support structure' for the heat coil of the unit and extending diametrically of the coil to terminatev in operative engagement with the switch mount.v

head portion above thev plane of the coil is engaged'by the bottom of the cooking utensil and urgedA downwardly to rotate the lever in switch operating" position as the utensil is' placed on the heating unit. I prefer to place the actuator post at the' center of theheat coil and arrange the lever pivot point so that the mechanical advantage attained thereby insures operation of the switch even when' small cooking vessels' are used, while permitting enough resistance to operation to avoid switch actuation when an empty vessel of average' size is placed on' the unit.

Other features and advantages of my invenn tion will;v be apparent from the following detailed description. of' a presently preferred embodiment, read in conjunction with the accompanying drawing' in which:

Figure 1 is a fragmentary top plan view of an4 electric range surface unit showing a signal switch and actuator applied thereto; Figure 2 is a vertical elevation of'the unit of Figure 1; Figure' 3` is anv end elevation of the switch element looking in the direction ofV `the' arrows 3-3 of Figure`A 2"; and Figure 4 is a vertical section of the switch lever andi actuator taken on lines 4-4 of Figure 2.

In Figure 1 a surface heating unit of an electric range comprises a heat coil in which one or morel heating elements 2 are arranged spirally to occupy a common plane suitably above and parallel with the cooking top` 370i the range. The heating elements are f' the conventional sheathed conductor type and may be arranged inV the fashion ofthe similar elements shown in Sharpv Reissue Patent- 2"2,l`7"7 ofv September 8, 1942.

Theheating elements are maintained inv planar relationshipy by agrid or support having a plurality of rigid arms 4- extending substantially ra dially from the center of the heating unit.

wThe arms in turn are supported by a ring 5 which rests on the cooking top 3v about the mar-f gin. of the opening provided in said top to accommodate the surfacev heating unit. The rel mits' the removal' of the' conventional reector v pan P (fragmentally shown in Figures l and 2) which customarily occupies the well below the surface heating unit. Accordingly, the rigid end portions 1 of the respective heating elements project through a cutaway portion of the reflector pan, as shown in said Sharp Reissue patent, and through suitable openings in a downwardly extending rigid member 8 comprising a portion of a hinge structure 9 which rotates about a hinge pintle I carried by a hinge bracket II xed by conventional means (not shown) to the frame of the range. A leaf spring I2 may be employed to bias the heating unit into its normal position parallel to the range top. The foregoing construction is conventional and forms no part of the present invention.

As the switch element of the signal actuating mechanism comprising my invention, I prefer to` use a mercury in glass cartridge I4 of the well known type in which a pair of electrodes are sealed in mutually spaced relationship within the glass envelope and the circuit is completed thereacross by a globule of mercury which travels between open and closed circuit positions as the envelope is tilted about a pivot perpendicular to the path of travel o the mercury. I consider this switch type preferable to conventional mechanically actuated make and break switches for reasons, among others, that the contacts are` hermetically sealed and thus completely protected against fouling by grease lms which may accumulate over extended periods, the switch is easily removed as a unit for inspection and replacement, and the shock hazard is entirely eliminated. It should be understood, however,

that I `do not preclude the use of other switch types, although I consider it important thatthe contacts be completely enclosed. The switch contacts are in a suitable manner connectedto the lead I5 which is suitably in a circuit embodying a signal device placed adjacent each ycontrol switch for the respective heating units. As previously noted, the control switches are usually mounted on the backsplasher of the range, and it will be understood that the signaling device may comprise an electric lamp associated with a switch such as shown in U. S. Patent No. 2,440,063 granted April 20, 1948, to' John L. Andrews.

A switch of the mercury in glass type may be easily mounted for operation as shown in Figures 2 and 3. I utilize a bracket I6 secured to the hinge element 8 and on a rigid wal1 I'I. of

said bracket I pivotally ax a cam plate I8. ,The

pivot may advantageously be a rivet 2|) or equivalent. 'Ihe switch envelope and the associated conductor I5 are removably supported in a bracket 2| which may be spot welded to the plate I8. It will be understood that the bracket 2| is of springable metal so that the switch envelope and the lead I5 therefrom may be snapped into place and readily removed. The Operation of the switch from open to closed'circuit position ment in the full line Figure 3 position in which the mercury globule is at the end of the glass envelope opposite to the terminals thereof. In other words, spring 26 maintains the switch in open circuit position.

I prefer to aflix the lever actuator directly to the lever. An eiiicient actuator may be in the form of a sheet metal column 28, the bottom portion of which extends beneath lugs 30 stricken outwardly from lever 22 and is welded or otherwise secured to said lugs. The column terminates in a convex cap 3| which normally occupies a plane substantially above that of the heating element as shown in Figure 2. Lateral stability is given to said column by the fingers 32 struck inwardly from opposite sides thereof to lie closell7 adjacent the sides of the arms 4 as shown in Figure 4. Cap 3| may be secured to column 28 by any suitable means after the heating elements 2 have been placed on the supporting structure.

When a cooking utensil is placed on the surface unit, it will urge the actuator downwardly, thereby rotating the lever 22 counterclockwisek of Figure 2. Arm member 23 will drive downwardly along slot 24 and will cam the mounting plate'A The car- I into rotation about the pivot 20. tridge Id will tilt sharply in the direction suggested in dotted lines in Figure 3, and the mercury globule will travel to the opposite end of the` cartridge to complete the circuit across the switch terminals. This will serve to complete the circuit to the signallight at the switch (not shown) and designate the backsplasher control switch associated with the particular lheating element. I prefer that the lever arrangement be of the second or-der as illustrated because advantage may be taken of substantially the maximum diameter ofthe surface unit and mechanical advantages may be established so that although a small cooking utensil placed on the heating unit will have sufficient weight, consideringA its contents, to actuate the switch, an empty utensil of average size will not be of suiiicient weight to move the switch to closed circuit position. It should be understood, of course, that the foregoing comment applies to conventional relatively light weight sauce pans, tea kettles, or the like which frequently are left empty on lthe cook stove and not to frying pans or heavy cooking pots Which ordinarily are stored away.

` It will thus be seen that I have provided ya simple switch actuating construction which isA substantially wholly based upon stamped metal parts capable of assembly in mass production .by workmen of ordinary skills. The switch and its actuator are made a part of the surface unit supis accomplished by a lever 22 pivotally attached to a supporting arm 4, as by the ear 22a and rivet 22h.. Advantageously, lever 22 is of light sheet metal stock which is formed in inverted U fashion for rigidity. The lever extends diametri-L cally of the heating element and terminates in an offset arm 23 which projects through a guide slot 24 in plate I'I and through a cam slot 25 formed in plate I8 and angularly intersecting the slot 24. A spring 26 xed to bracket I5 yand bearing against the underside of the arm 23 urges the arm upwardly toward the heating element and in such' position maintains the switch eleport structure so as not to interfere with the movement of the surface unit about its pivot..V

The switch cartridge and lead are shielded by the plates I'I and I3 from heat radiated from the surface heating unit, and by their disposition below the cooking top 3, are protected againstv accidental physical damage.

while there has been described what is at present considered to be the preferred embodiment of the invention, it will be understood that various f modications may be made therein,kand it is intended to cover in the appended claim all such modifications as fan within the true spirit and scope of the invention,

What I claim as new and desire to secure by.,

Letters Patent of the United States is:

1. In an electric range having a heat coil supstructure being carried by a, hinge member xed to the range for pivotal movement of the coil support with respect to said range, an electrical switching system comprising a cam plate pivotally affixed to a wall of said hinge member, a switch unit of the mercury contact type, means for detachably securing said switch unit to said cam plate to be rocked thereby between open and closed circuit positions, a guide slot in said hinge wall member, an elongated cam slot in said cam plate angularly intersecting said guide slot, a lever pivotally carried by said heat coil support near the radially outermost portion thereof and extending diametrically beneath said heat coil, said lever having an arm extending through said guide slot and said cam slot whereby movement of said arm accompanying rotation of said lever will rock said cam plate and the switch unit carried thereby, spring means normally biasing said lever to urge said cam plate into open circuit switch position, and plunger means embracing said lever and projecting upwardly therefrom through the central portion of said heat coil to be engaged and urged downwardly by a cooking utensil placed on said heat coil, to rotate the lever in a direction moving the switch to closed circuit position.

2. Switching means according to claim 1, in which said plunger means straddles said heat coil supporting means and has iingers engageable with side walls of said supporting means for lateral stability of said plunger means.

3. In an electric range having a heat coil supported on a structure carried by a hinge member xed to the range for pivotal movement of the coil support with respect to said range, an electrical switching system comprising a cam plate pivotally aixed to a wall of said hinge member, a switch unit operable between open and closed circuit positions upon rocking the unit in one or another direction, means for detachably securing said switch unit to said cam plate, whereby the switch unit remains in fixed relation to said heat coil during any pivotal movement of said heat coil support, a guide slot in said hinge wall member, an elongated cam slot in said cam plate angularly intersecting said guide slot, a lever DiV- otally carried by said heat coil support beneath said coil and having an arm extending through said guide slot and said cam slot whereby movement of said arm accompanying rotation of said lever will rock said cam plate and the switch unit carried thereby, spring means normally biasing said lever to urge said cam plate into open circuit switch position, and plunger means xed to said lever and projecting upwardly through the central portion of said heat coil to be engaged and urged downwardly by a cooking untensil placed on said heat coil, to rotate the lever in a direction moving the cam plate into closed circuit switch position.

4. In an electric range having a heat coil supported on a structure carried by a hinge structure iixed to the range for pivotal movement into angular relation with said range, a switch of the mercury in glass type, means for pivotally mount-1 ing said switch member on said hinge structure, said switch member being rotatable between open and closed circuit positions, cam means for rotating said switch member, a lever pivotally carried by said heat coil support beneath said heat coil and extending into operative association with said cam means to rotate said switch member upon rotation of said lever, spring means normally biasing said lever to urge said switch member into open circuit position, and plunger means carried by said lever and projecting upwardly through the central portion of said heat coil to terminate in a cap disposed above the upper plane of said heat coil to be engaged and urged downwardly by a cooking utensil placed on said heat coil, thereby to rotate the lever in a direction moving the switch to closed circuit position.

5. In an electric range, a heating unit including a heating element arranged in substantially at coil form, rigid support means for said element and hinge means having one element secured to said range and a second element secured to said support means whereby said heating unit may be rotated relative to said range; an electric switch, means for mounting said switch on said second hinge element to maintain a fixed position of said switch relative to said heating element at any position of the heating unit relative to said range; means for actuating said switch between open and closed circuit positions; a lever carried by said support means and extending below one of said hinge elements into engagement with said switch `actuator for operating said switch to open or closed circuit position according to the direction o rotation of said lever; lever actuating means extending from said lever between convolutions of said heating element to a terminus above the plane of said element, whereby a cooking vessel placed on said heating element will engage said actuating means and by its weight depress said actuating means to rotate said lever in switch circuit closing direction; and spring means engaging said lever to bias the lever into rotation in switch circuit opening direction upon removal of said vessel from said heating element, said last-named direction of rotation restoring the lever actuating means for re-engagement by a cooking vessel, said hinge element interrupting said rotation to establish a xed relation of said lever actuating means relative to the plane of said heating element.

KEMPER M. HAMMELL.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,901,028 Green Mar. 14, 1933 FOREIGN PATENTS Number Country Date 246,217 Switzerland Sept. 30, 1944 

